Significant Decrease In Fecundity Research Articles

Response of fruit fly (Drosophila pseudoobscura) to diet manipulation of nutrient density

AbstractCaloric intake can greatly affect many aspects of an organism's life. A deficiency of calories can lead to stress resulting in decreased fecundity, insufficient calories to maintain tissues and increased lifespan. Conversely, increasing caloric density increases fecundity and decreases lifespan. Despite decades of work exploring food quality and quantity on physiology in the model species Drosophila melanogaster Meigan 1830 (Diptera: Drosophilidae) and the melanogaster group in general, relatively little work explores the physiological responses to diet manipulation in other Drosophila species, like the obscura species group. Here, we looked at the effects of five different caloric densities (0.5×, 0.75×, 1.0×, 1.5× and 3.0×) on food intake, body weight, body fat, fecundity and longevity in D. pseudoobscura Frolova & Astaurov, 1929 (Diptera: Drosophilidae). Comparing longevity and fecundity across diets, we found that heavy caloric concentration (3.0×) decreases lifespan and that calorie restriction (0.5× and 0.75×) led to significant decreases in fecundity and body weight. However, calorie concentration did not significantly increase D. pseudoobscura body fat. By expanding our understanding of the physiological responses to diet stress to D. pseudoobscura, we establish the framework for comparative work across Drosophila species. With this information, we can then identify which physiological responses to diet manipulation might be most conserved and comparable across species.

The sublethal concentration of acetamiprid suppresses the population growth of 2 species of wheat aphids, Sitobion miscanthi and Schizaphis graminum (Hemiptera: Aphididae).

Sitobion miscanthi and Schizaphis graminum (Rondani) are the 2 main aphid species that occur simultaneously, causing significant loss to wheat production. Acetamiprid has been used to control a variety of pests, including aphids. In this study, the sublethal effect of acetamiprid on S. miscanthi and S. graminum was evaluated using life-table analyses. The results showed that acetamiprid has a high toxicity to S. miscanthi and S. graminum with a LC50 of 1.90 and 3.58 mg/L at 24 h, respectively. The adult longevity and fecundity of S. miscanthi and S. graminum F0 generation were significantly reduced after being exposed to a sublethal concentration of acetamiprid. Additionally, the sublethal concentration of acetamiprid had negative transgenerational effects on S. miscanthi and S. graminum, which showed a significant decrease in fecundity and population life-table parameters involving age-stage-specific survival rate (sxj), age-specific survival rate (lx), and intrinsic rate of increase (r). Furthermore, the population projections showed that the total population size of S. miscanthi and S. graminum was significantly lower in the aphid group exposed to sublethal concentration of acetamiprid compared to the control group. These results suggest that sublethal concentration of acetamiprid suppresses the population growth of S. miscanthi and S. graminum. This finding is beneficial to the control of wheat aphids, and is important to fully understand the role of acetamiprid in integrated pest management.

Disruption of microRNA pathway core genes inhibits molting and reproduction of the cigarette beetle, Lasioderma serricorne.

MicroRNA (miRNA) pathway genes have been widely reported to participate in several physiological events in insect lifecycles. The cigarette beetle Lasioderma serricorne is an economically important storage pest worldwide. However, the functions of miRNA pathway genes in L. serricorne remain to be clarified. Herein, we investigated the function of molting and reproduction of the miRNA pathway in L. serricorne. LsDicer-1, LsArgonaute-1, LsLoquacious and LsExportin-5 were universally expressed in adults, whereas LsPasha and LsDrosha were mainly expressed in the pupae. The genes presented different patterns in various tissues. Silencing of LsDicer-1, LsArgonaute-1, LsDrosha and LsExportin-5 resulted in a high proportion of wing deformities and molting defects. Silencing of LsDicer-1, LsArgonaute-1, LsPasha and LsLoquacious affected the development of the ovary and the maturation of oocytes, resulting in a significant decrease in fecundity. Further investigation revealed that the decreases in LsDicer-1 and LsArgonaute-1 expression destroyed follicular epithelia and delayed vitellogenesis and oocyte development. In addition, the expression levels of several miRNAs (let-7, let-7-5p, miR-8-3p, miR-8-5p, miR-9c-5p, miR-71, miR-252-5p, miR-277-3p, miR-263b and Novel-miR-50) were decreased significantly after knockdown of these miRNA pathway core genes, indicating that they played important roles in regulating miRNA-mediated gene expression. The results indicate that miRNA pathway genes play important roles in the molting, ovarian development and female fecundity of L. serricorne, and thus are potentially suitable target genes for developing an RNAi strategy against a major pest of stored products. © 2024 Society of Chemical Industry.

Evaluation of chemosterility effect of different insect growth regulators on Bactrocera zonata population.

The indiscriminate application of synthetic pesticides on horticultural plants for the management of Bactrocera zonata has both economic and environmental implications due to the biomagnification of harmful residues in humans via the food chain. This necessitates the use of some eco-friendly control measures such as insect growth regulators (IGRs) as an alternative. A laboratory experiment was laid out to determine the potential chemosterilant effect of five IGRs including pyriproxyfen, novaluron, lufenuron, buprofezin, and flubendiamide at six different concentrations on B. zonata after treating adult diet. Using the oral bioassay, B. zonata were fed on IGRs impregnated diet (50-300 ppm/5 mL diet) which was replaced with the normal diet after 24 h of feeding. Ten pairs of B. zonata were placed in a separate plastic cage accommodating an ovipositor attractant guava for eggs collection and calculation. An analysis of the result revealed that fecundity and hatchability were higher at a low dose and vice versa. Lufenuron at 300 ppm/5 mL of diet significantly decreased the fecundity rate (31.1%) as compared to pyriproxyfen, novaluron, buprofezin and flubendiamide, which had 39.3%, 39.3%, 43.8%, and 47.5%, respectively. The lowest hatchability (19.9%) was noted in lufenuron treated diet followed by pyriproxyfen, novaluron, buprofezin, and flubendiamide, which had 22.1%, 25.0%, 30.9%, and 31.6%, respectively. Furthermore, in a population of crosses between the lufenuron treated male and female, a significant decrease in fecundity (45.5%) and hatchability (51.7%) was noted as compared to other IGRs. Overall, this study identified the chemosterilant potential of lufenuron on the population of B. zonata which can be integrated for its management strategy.

Molecular Characterization of Vitellogenin and Its Receptor in Spodoptera frugiperda (J. E. Smith, 1797), and Their Function in Reproduction of Female.

The fall armyworm Spodoptera frugiperda is a highly polyphagous invasive pest. The strong reproductive capacity is an important factor in the rapid colonization and expansion of S. frugiperda. Vitellogenin (Vg) and vitellogenin receptor (VgR) play important roles in insect reproduction. As the precursor of vitellin (Vn), Vg provides essential nutrition for embryonic development, and VgR mediates the uptake of Vg by oocytes. In this context, we cloned and characterized these two genes of S. frugiperda (SfVg and SfVgR) and evaluated their expression profiles in different developmental stages and tissues. The RNA interference experiment was used to investigate their function in vitellogenesis. The ORF values of SfVg and SfVgR were 5250 and 5445 bp, encoding 1749 and 1815 amino acid residues, respectively. The qRT-PCR results revealed that both SfVg and SfVgR were highly expressed in female adults; SfVg was specifically expressed in the fat body, whereas SfVgR was highly expressed in the ovary. In addition, the depletion of either SfVg or SfVgR hindered oocyte maturation and ovarian development, leading to a significant decrease in fecundity. The present study reveals the importance of SfVg and SfVgR in the vitellogenesis of S. frugiperda, laying a theoretical foundation for the development of pollution-free pest control strategies with SfVg and SfVgR as new targets.

Hyperactivation of the proteasome in Caenorhabditis elegans protects against proteotoxic stress and extends lifespan

Virtually all age-related neurodegenerative diseases (NDs) can be characterized by the accumulation of proteins inside and outside the cell that are thought to significantly contribute to disease pathogenesis. One of the cell’s primary systems for the degradation of misfolded/damaged proteins is the ubiquitin proteasome system (UPS), and its impairment is implicated in essentially all NDs. Thus, upregulating this system to combat NDs has garnered a great deal of interest in recent years. Various animal models have focused on stimulating 26S activity and increasing 20S proteasome levels, but thus far, none have targeted intrinsic activation of the 20S proteasome itself. Therefore, we constructed an animal model that endogenously expresses a hyperactive, open gate proteasome in Caenorhabditis elegans. The gate-destabilizing mutation that we introduced into the nematode germline yielded a viable nematode population with enhanced proteasomal activity, including peptide, unstructured protein, and ubiquitin-dependent degradation activities. We determined these nematodes showed a significantly increased lifespan and substantial resistance to oxidative and proteotoxic stress but a significant decrease in fecundity. Our results show that introducing a constitutively active proteasome into a multicellular organism is feasible and suggests targeting the proteasome gating mechanism as a valid approach for future age-related disease research efforts in mammals.

Oxidative stress–mediated synergistic deleterious effects of nano- and microplastics in the hypoxia-conditioned marine rotifer Brachionus plicatilis

While pollution due to nano- and micro-sized plastics (NMPs) and hypoxic conditions both occur in coastal areas, the deleterious potential of co-exposure to hypoxia and NMPs (hypoxia and micro-sized plastics, HMPs; hypoxia and nano-sized plastics, HNPs) is largely unclear. Here, we provide evidence for multigenerational effects of HMP and HNP in the marine rotifer Brachionus plicatilis by investigating changes in its life traits, antioxidant system, and hypoxia-inducible factor (HIF) pathway using an orthogonal experimental design, with nanoscale and microscale particles measuring 0.05 μm and 6.0 μm in diameter, respectively, and hypoxic conditions of 0.5 mg/L for six generations. Combined exposure to NMPs and hypoxia caused a significant decrease in fecundity and overproduction of reactive oxygen species (ROS). The HIF pathway and circadian clock genes were also significantly upregulated in response to HMP and HNP exposure. In particular, synergistic deleterious effects of HNP were evident, suggesting that size-dependent toxicity can be a major driver of the effects of hypoxia and NMP co-exposure. After several generations of exposure, ROS levels returned to basal levels and transcriptomic resilience was observed, although rotifer reproduction remained suppressed. These findings help eluciating the underlying molecular mechanisms involved in responses to plastic pollution in hypoxic conditions.

Dengue Virus-2 Infection Affects Fecundity and Elicits Specific Transcriptional Changes in the Ovaries of Aedes aegypti Mosquitoes.

Dengue fever (DF), caused by the dengue virus (DENV), is the most burdensome arboviral disease in the world, with an estimated 400 million infections each year. The Aedes aegypti mosquito is the main vector of DENV and transmits several other human pathogens, including Zika, yellow fever, and chikungunya viruses. Previous studies have shown that the pathogen infection of mosquitoes can alter reproductive fitness, revealing specific vector-pathogen interactions that are key determinants of vector competence. However, only a handful of studies have examined the effect of DENV infection in A. aegypti, showing a reduction in lifespan and fecundity over multiple blood meals. To provide a more comprehensive analysis of the impact of DENV infection on egg laying and fecundity, we assessed egg laying timing in DENV-2 blood-fed mosquitoes (infected group) compared to mock blood-fed mosquitoes (control group). We confirmed a significant decrease in fecundity during the first gonadotrophic cycle. To further investigate this phenotype and the underlying DENV-2 infection-dependent changes in gene expression, we conducted a transcriptomic analysis for differentially expressed genes in the ovaries of A. aegypti infected with DENV-2 vs. mock-infected mosquitoes. This analysis reveals several DENV-2-regulated genes; among them, we identified a group of 12 metabolic genes that we validated using reverse transcription-quantitative PCR (RT-qPCR). Interestingly, two genes found to be upregulated in DENV-infected mosquito ovaries exhibited an antiviral role for DENV-2 in an Aedes cell line. Altogether, this study offers useful insights into the virus-vector interface, highlighting the importance of gene expression changes in the mosquito’s ovary during DENV-2 infection in the first gonadotrophic cycle, triggering antiviral responses that may possibly interfere with mosquito reproduction. This information is extremely relevant for further investigation of A. aegypti’s ability to tolerate viruses since virally infected mosquitoes in nature constitute a powerful source of supporting viruses during intra-epidemic periods, causing a huge burden on the public health system.

Characterizing toxicity pathways of fluoxetine to predict adverse outcomes in adult fathead minnows (Pimephales promelas)

Current ecotoxicity testing programs are impeded as they predominantly rely on slow and expensive animal tests measuring adverse outcomes. Therefore, new approach methodologies (NAMs) increasingly involve short-term mechanistic assays that employ molecular endpoints to predict adverse outcomes of regulatory relevance. This study aimed to elucidate the application of NAMs in adult fathead minnows using fluoxetine (FLX) as a model compound. Fish were exposed to three FLX concentrations (measured: 2.42, 10.7, and 56.7 μgL−1) and a control. After 96 h, molecular toxicity signatures were characterized using proteomics and transcriptomics analyses in livers and brains of a sub-set of fish. The remaining fish were sampled at 21 days and assessed for liver histopathology and morphometric measurements. Fecundity was monitored throughout the study. In the livers, 56.7 μgL−1 FLX caused enrichment of PPAR signaling in the proteome and fatty acid-related pathways in the transcriptome, potential upstream responses that led to lipid-type vacuolation of hepatocytes, observed via histopathology. Upregulated genes in the brain suggested alterations in serotonin-related signaling processes and reproductive behaviour, which may explain the observed significant decrease in fecundity. While the relationships between molecular responses and adverse outcomes remain complex, this research provided important insights into the mechanistic toxicity of FLX.

Low Iodine Intake May Decrease Women's Fecundity: A Population-Based Cross-Sectional Study.

Salt iodization is one of the most cost-effective strategies to eliminate iodine deficiency disorders (IDD). However, China’s dismantling of salt monopoly has reduced the availability of iodized salt in the susceptible population in pregnancy, which might cause IDD and have adverse health effects on both themselves and their offspring. The aim of our study was therefore to explore the association between IDD and women’s reproductive health. This is a population-based cross-sectional study conducted in 2018 in Zhejiang Province, China. A total of 1653 pregnant women participated in this study. Median urinary iodine concentration (UIC) in the population was used to assess iodine intake. Cox regression analyses were used to estimate the association between iodine intake and time to pregnancy, which was indicated with fecundability ratio (FR) and 95% confidence interval (CI). The percentage of participants with iodine deficiency who had been waiting longer than 13 months to get pregnant (20%; median UIC 119.6 μg/L) was significantly higher than those with iodine sufficiency (14%; median UIC 147.1 μg/L). A significant decrease in fecundity was observed in participants with iodine deficiency (FR, 0.820; 95% CI, 0.725−0.929) than those with iodine sufficiency. These findings indicate the importance of ongoing monitoring of iodine nutrition in women of reproductive age. Keeping a safe and optimal level of iodine nutrition during pregnancy should be emphasized.

Sublethal effects of short-term and long-term exposure to triflumezopyrim on the small brown planthopper Laodelphax striatellus (Hemiptera: Delphacidae)

The small brown planthopper (SBPH), Laodelphax striatellus (Fallén), is an economically important pest that affects rice. In this study, we analyzed the sublethal effects of triflumezopyrim on the biological and demographic parameters of SBPHs in the laboratory. Treatment of third-instar SBPHs with the LC30 of triflumezopyrim prolonged the lives of male adults. The F0 individuals exhibited a significant decrease in fecundity (25.8%) after exposure to triflumezopyrim. The fecundity and egg hatchability of the progeny (F1 individuals) were not significantly affected by treatment with the LC30 of triflumezopyrim, but the mean generation time increased significantly. In addition, the intrinsic rate of increase, finite rate of increase, net reproductive rate, and doubling time did not exhibit any significant changes. However, long-term exposure to the LC75 of triflumezopyrim resulted in a significant decrease in the number of males in the SBPH population. The results of this study indicate that triflumezopyrim can be utilized in pest control programs for SBPHs.

Association between exposure to airborne particulate matter less than 2.5 μm and human fecundity in China

BackgroundWhether exposure to airborne particulate matter less than 2.5 μm (PM2.5) could impact human fecundity is unclear. We aimed to evaluate the potential impact of PM2.5 exposure on time to pregnancy (TTP) and the prevalence of infertility in the general Chinese population. MethodWe collected reproductive information, sociodemographic characteristics, and lifestyle data of 10,211 couples at risk of pregnancy from a large-scale community-based fertility survey in China. Then, we estimated each participant’s 1-year, 3-year, and 5-year average PM2.5 exposure levels based on remote sensing information. After adjusting for demographic, lifestyle, and environmental co-variables, discrete-time Cox regression models were used to estimate the fecundability odds ratio (FOR) per 10 μg/m3 change of PM2.5. We also estimated the odds ratio (OR) of infertility per 10 μg/m3 change of PM2.5, using logistic regression models. FindingsAmong the 10,211 couples, 6,875 (67%) had conceived spontaneously, with a median TTP of 5 months (interquartile range: 2–10 months). The median PM2.5 exposure was 56.8 μg/m3, with a wide range of 9.2–93.5 μg/m3. In Cox regression models, each increase of 10 μg/m3 in the 1-year average PM2.5 exposure was associated with a significant decrease in fecundity by 11% (FOR: 0.89; 95% confidence interval [CI]: 0.86–0.92). In logistic regression models, it was also associated with an 20% increased likelihood of infertility (OR: 1.20; 95% CI: 1.13–1.27). ConclusionPM2.5 exposure was associated with reduced human fecundity, presented by a longer TTP and higher odds of infertility, which might explain the increased infertility rates in areas with heavy PM2.5 pollution.

Fecundity and Infertility Among Women with Disabilities in the United States.

Background: Knowledge of fecundity and infertility in women with a disability (WWD) is limited. This study aims to compare the fecundity and infertility experiences of women with a self-identified disability, in domains of sensory (hearing and vision loss), cognitive (difficulty concentrating, remembering, and making decisions), and physical (difficulty walking or climbing stairs) disabilities, with those without a self-identified disability. Materials and Methods: Cross-sectional survey data from the National Survey of Family Growth (NSFG), 2011-2015, were analyzed. A final analytic sample of 383 women from the NSFG, aged 18-44 years, was included to study the fecundity rates of WWD and women without a disability, using the current duration approach. Results: Fecundity hazard ratios (FHRs) and the proportion of women experiencing infertility after 12 months of actively attempting pregnancy were reported for the comparison group and by each disability type. Women with a self-identified cognitive disability experienced significant decreases in fecundity (FHR = 0.56; 95% confidence interval [CI]: 0.30-0.88) when adjusting for age, education level, parity, living in a metropolitan area, and infertility services. Furthermore, the estimated proportion of infertile women without a disability was 0.38 (95% CI: 0.23-0.62) versus 0.51 (95% CI: 0.34-0.72) for women with a self-identified cognitive disability. Conclusions: Women with a self-identified cognitive disability experienced significant decreases in fecundity.

Genes associated with Parkinson's disease respond to increasing polychlorinated biphenyl levels in the blood of healthy females

Current ecotoxicity testing programs are impeded as they predominantly rely on slow and expensive animal tests measuring adverse outcomes. Therefore, new approach methodologies (NAMs) increasingly involve short-term mechanistic assays that employ molecular endpoints to predict adverse outcomes of regulatory relevance. This study aimed to elucidate the application of NAMs in adult fathead minnows using fluoxetine (FLX) as a model compound. Fish were exposed to three FLX concentrations (measured: 2.42, 10.7, and 56.7 μgL−1) and a control. After 96 h, molecular toxicity signatures were characterized using proteomics and transcriptomics analyses in livers and brains of a sub-set of fish. The remaining fish were sampled at 21 days and assessed for liver histopathology and morphometric measurements. Fecundity was monitored throughout the study. In the livers, 56.7 μgL−1 FLX caused enrichment of PPAR signaling in the proteome and fatty acid-related pathways in the transcriptome, potential upstream responses that led to lipid-type vacuolation of hepatocytes, observed via histopathology. Upregulated genes in the brain suggested alterations in serotonin-related signaling processes and reproductive behaviour, which may explain the observed significant decrease in fecundity. While the relationships between molecular responses and adverse outcomes remain complex, this research provided important insights into the mechanistic toxicity of FLX.

Rерrotoxiсity profiling of Bisрyribас Sodium, Pinoxaden and Spinosad Pesticides on Drosoрhilа mеlаnogаstеr

Present research exploration is attributed to reproductive toxicity evaluation of three synthetic agro-chemical pesticidal formulations viz: Bisрyribас Sodium, Pinoxaden and Spinosad, by implementing, test model, Drosophila melanogaster (2n=8). The target of present exploration is to evaluate reprotoxicity induced by selected pesticides. To accomplish the objectives of present research analysis, standardization of semilethal concentration LC 20 , had been considered by exposing second instar larvae to serial dilution of selected pesticides, for continuation of 24 hrs. Thereafter, considering co-relation between exposed concentration and mortality rate, exact values of LC 20 , had been calculated by probit analysis,which correspond to values 4.4 pl/ml for Sodium Bispyribac and 7.1pl/ml for Pinaxoden pl/ml for Bisрyribас Sodium, and 2 pl/ml for Spinosad. Subsequently, second instar larvae of fruit fly were exposed to sub lethal concentration, LC 20 of selected pesticides, for 24 hrs, by means of nutrition, adding to culture medium. Afterward, larvae molted into imago in normal culture medium, which were allowed to cross mate in three separate experimental sets, in triplicate with respective negative controls. In first set, both pesticide exposed male and female cross-mated. In second experimental set, treated male and normal female flies were allowed to crossmate, whereas in third experimental set, pesticide exposed females were allowed to mate with normal males. After comparison of fecundity rate in all experimental sets with natural population, it had been concluded that selected pesticides induced statistical significant decrease in fecundity, when scrutinized by Z-test (p<0.05). Additionally, it had been analysed that the male fruit flies were more susceptible than female fruit flies to selected pesticides.

Assessment of steroidogenic pathway components following exposure of L. palustris to the herbicide roundup or its components.

We are analyzing the effects of Roundup and its components on the pond snail, Lymnaea palustris. Roundup is a commonly used herbicide composed of the chemicals Glyphosate, POEA (a surfactant), and Diquat Dibromide (DD). By testing the effects of Roundup and its components on a hermaphroditic organism such as L. palustris, one can observe significant alterations in reproductive output as well as shifts in hormone levels or steroidogenic pathway components following exposure to these chemicals. Preliminary results from our laboratory showed chronic Roundup treatment yielded significantly decreased testosterone levels as well as altered estradiol and progesterone levels. Additionally, chronic treatments reduced expression of StAR enzyme, especially within the ovotestis. In the current study, snails (N=60) were chronically treated in solutions of pond water supplemented with RoundUp, DD, POEA, or Glyphosate. During the treatment period, snail fecundity and mortality were noted on a biweekly basis for each treatment group. After the treatment period, the kidney, gonadodigestive complex, and brain were harvested from each snail to analyze the expression of StAR, and p450AROM enzymes via Western blotting. Standardized amounts of protein from control and treated animals were compared during the analysis for each organ. In a concurrent study, testosterone, cortisol, and estradiol levels were tested at the three and six week marks by enzyme immunoassay. A significant decrease in fecundity was observed in snails in all treatment groups. Shifts were observed in both hormone and protein levels when comparing the results of the treatment groups to the control group.

Laboratory evaluation of Lactobacillus johnsonii CRL1647 metabolites for biological control of Musca domestica

AbstractThe house fly, Musca domestica L. (Diptera: Muscidae), is a key problem in animal producing and rearing areas. Currently, the use and abuse of chemical pest‐control compounds has generated resistance in M. domestica and, hence, new approaches are required. In this work, the potential entomopathogenic activity of Lactobacillus johnsonii Fujisawa et al. CRL1647 was evaluated against M. domestica, under laboratory conditions. Bioassays were done for three consecutive years using bacterial cell suspensions (CS) and cell‐free supernatants (CFS) under controlled conditions (27 ± 1 °C, 57 ± 2% r.h., and L12:D12 photoperiod). Both the CS and CFS displayed high levels of larvicidal (96%) and pupicidal (97%) activities. Chemical characterization of the CFS revealed that the bioactive metabolites are acidic compounds, not affected by thermal treatment or by trypsin. Organic acids were identified and quantified by high‐performance liquid chromatography (HPLC); only lactic acid (129.7 ± 1.0 mM), acetic acid (37.3 ± 0.8 mM), and phenyllactic acid (0.3 ± 0.1 mM) were detected. A significant decrease in fecundity of the house flies was observed in females from larvae fed on CFS; male fertility was not affected. Interestingly, only the mixture of organic acids exerted the biological effects. These results suggest that the metabolites synthesized by L. johnsonii CRL1647 can be used in a novel biocontrol strategy against house flies.

Biological Characteristic of Brachynema germari (Hemiptera: Pentatomidae): Comparative Study of Composite and Natural Diet.

This research was conducted to develop a composite diet and compare its effects on developmental time, fecundity, survival rate, and life table parameters of pistachio green stink bug, Brachynema germari Kolenati (Hemiptera: Pentatomidae) with a natural diet. The biological parameters of this pest were investigated using two-sex, age-stage life table theory on both composite and natural diets (25 ± 1°C, 50 ± 10% relative humidity, and a photoperiod of 16:8 [L:D] h). Based on the preliminary studies, the combination of the green beans ( Phaseolus vulgaris L.), sunflower seeds ( Helianthus annuus L.), and wild rue capsules ( Peganum harmala L.) was introduced into a composite diet. There was no significant difference between the longevity of each stage on diet treatments, but the mean fecundity of female fed on composite diet was about 196.48 ± 12.02 (eggs), which indicated a significant decrease than the fecundity of female fed on the natural diet (265.81 ± 11.67 eggs; P = 0.05, t -test). Also, main parameters of life table ( r , R 0 , T , and λ) for composite and natural diets were about 0.0863 ± 0.0031 d -1 , 89.03 ± 13.33 eggs, 51.987 ± 0.536 d, and 1.091 ± 0.0034 d -1 and 0.1023 ± 0.003 d -1 , 128.75 ± 17.56 eggs, 47.454 ± 0.439 d, and 1.1077 ± 0.0037 d -1 , respectively. There was a significant difference between these four parameters on both diets. Despite a significant decrease in fecundity with using composite diets, this diet can satisfy our needs now and the laboratory rearing of pistachio green stink bug did not stop over the year in the absence of host weeds and insect did not diapause.

Effect of gamma radiation on life history traits of Aedes aegypti (L.)

Aedes aegypti is an important vector for Dengue and Dengue hemorrhagic fever. Considering its medical importance and its relevance as a model system, this study was undertaken to evaluate the impact of different doses of gamma radiation for three generations of A. aegypti. Two to three days old virgin males of A. aegypti were irradiated with 15 doses of gamma radiation, ranging from 1 to 50Gy and were immediately mass mated with the same aged virgin females. Observations were made for changes on their life history traits, particularly fecundity, hatchability, adult emergence, sex ratio and longevity, for three generations. Adult males exposed 30, 35, 40, 45 and 50Gy doses showed a significant decrease in fecundity in F0 generations. While hatchability was observed to have decreased with increasing radiation doses from 3Gy onwards in the F1 generation, samples irradiated with 30, 35, 40, 45 and 50Gy maintained significant decline in hatchability in their succeeding generations, F2 and F3 also. Similarly, a decline was observed in adult emergence from 3Gy onwards in all three generations. A male favoring sex ratio distortion was observed at the doses of 35, 40, 45 and 50Gy in all three generations. Following exposure to 4Gy, parental males and the resultant progeny showed increased longevity by 10.56 and 8.66days respectively. Similarly, the F1 generations of samples irradiated with 30, 35 and 40Gy exhibited an increase in longevity by 7.16, 7.44 and 6.64days respectively. Dose response curve for fertility among the three generations was drawn and presented. The effect of radiological exposure on the life history traits of A. aegypti varies with dose for the three generations studied. These results have potential implications in mutational studies and risk assessment and also contribute to a better understanding towards employment of the sterile insect technique in A. aegypti, plausibly paving the way to an effective mosquito genetic control program.

Rice stripe virus counters reduced fecundity in its insect vector by modifying insect physiology, primary endosymbionts and feeding behavior.

Virus-vector relationships can be complex and diverse as a result of long-term coevolution. Understanding these interactions is crucial for disease and vector management. Rice stripe virus (RSV) is known to be transovarially transmitted within its vector, Laodelphax striatellus, and causes serious rice stripe disease. In RSV-infected L. striatellus, we found contrasting changes in vector fecundity, physiology, primary endosymbionts (i.e. yeast-like symbionts, YLS) and feeding behavior that can interact to affect the spread of RSV. RSV-infected L. striatellus exhibited a significant decrease in fecundity that could lead a reduction of viruliferous individuals in populations. As a potential response to this loss, RSV infection also significantly shortened nymphal stage duration, which can strengthen RSV vertical circulation in L. striatellus populations and promote RSV spreading by adult migration and dispersal. Down-regulated JHAMT and up-regulated CYP307A1 in the juvenile hormone and ecdysteroid pathways, respectively, were linked to accelerated development. RSV-infected adults were also found to have higher body weight in conjunction with increased YLS abundance. Furthermore, prolonged host plant phloem exposure to salivation by RSV-infected adults should further enhance RSV horizontal transmission. Our study highlights potential strategies of RSV in enhancing its transmission, and provides new insights into the complexity of virus-vector interactions.